In stators for rotary electric machines such as electric motors or generators, a varnish has been impregnated into a stator winding and cured in order to fix a stator winding that is mounted to a stator core, in order to ensure insulation between the stator core and the stator winding, and also in order to increase heat radiating characteristics of the stator winding.
Conventional methods for impregnating varnish into stator windings include impregnating a varnish into coil ends of a stator winding by dripping varnish from above onto the coil ends while rotating a stator core around a central axis such that the central axis is horizontal, and impregnating the varnish inside slots from the coil ends using capillary action (see Patent Literature 1, for example).
Other conventional methods for impregnating varnish into stator windings include impregnating a varnish into coil ends by dripping varnish from above onto coil ends of a stator winding such that a central axis is vertical, and impregnating the varnish inside slots from the coil ends using capillary action (see Patent Literature 2, for example).
In recent years, compactness and high output have been required in rotary electric machines such as electric motors or generators. With regard to downsizing rotary electric machines of this kind, stator windings that have concentrated windings in which conductor wires are wound onto individual stator core teeth have been used with a view to downsizing coil ends that do not generate effective magnetic flux. Stator windings of this kind are generally constituted by concentrated winding coils that are produced by disposing insulators on two axial ends of teeth of core segments that have a single tooth, and winding conductor wires so as to do laps around the teeth using the insulators as bobbins. In concentrated winding coils that are produced in this manner, because the coil ends are hidden by the insulators when viewed from a radial direction, the coil ends have been impregnated with varnish using the varnish impregnating method that is described in Patent Literature 2.